New 3D Map Reveals the Dusty Structure of the Milky Way Galaxy

Astronomers are learning more about the Milky Way than ever before. They've created a detailed, 3D map of the dusty structure as seen from Earth's northern hemisphere. The new map could help astronomers in future studies of this region of space.

Dust and gas that make up the Interstellar Medium fill the space between stars in galaxies. More specifically, the dust in the Interstellar Medium (ISM) is shaped by turbulent flows that form intricate fractal structures on scales ranging from thousands of light years to just hundreds of kilometers. The researchers didn't measure the dust itself to create the map, though. Instead, the scientists used observations of more than 38 million stars in order to estimate how much starlight has been obscured by the ISM and thus how much dust lies in our line of sight to each star.

"Because the solar system is embedded in the disk of the Milky Way, our view of it is choked with dust, with the result we know less about its internal structure than we do about some external galaxies, such as M31 in Andromeda," said Janet Drew, one of the researchers, in a news release. "In this Northern survey, we are mainly looking at the parts of the Galactic disk that lie outside the sun's orbit around the Galactic Center. This 3D map demonstrates with greater force than existing 2D maps that dust in the outer disk does not trace the Perseus spiral arm and other expected structures in a simple way."

The new map actually shows how extinction builds with distance away from the sun in any part of the surveyed northern Milky Way. In fact, it catches detail on an angular scale about seven times finer than the angular size of the moon. The fractal nature of the ISM is also visible on the map, as are large-scale features, such as star-forming molecular clouds and bubbles of ionized gas around clusters of hot stars.

"We can see a number of specific features, including the Rosette Nebula and the star-forming belt in the Perseus Arm of the Milky Way," said Stuart Sale, one of the researchers, in a news release. "Our location within the Milky Way means that we can study the ISM in far greater detail than for any other galaxy. The knowledge that we gain from studying our own galaxy can be subsequently applied to others."